Table 2.

RR and 95% CI for BCC by tertiles of plasma omega-3 and omega-6 concentrations, tumor-based analysis in all participants of the Nambour Skin Cancer Study, and in those with a personal history of skin cancer, 1997–2007

All participants (n = 1,191)Participants with previous skin cancers (n = 398)
Tertiles of plasma phospholipid concentrationsTertiles of plasma phospholipid concentrations
Fatty acidsTertile 1Tertile 2Tertile 3PtrendaTertile 1Tertile 2Tertile 3Ptrenda
Sum of omega-3, μg/mLb<48.5648.56–63.20>63.20<48.5648.56–63.20>63.20
Sum of tumors, n208244248155174179
Basic RR (95% CI)c1.000.96 (0.68–1.34)0.90 (0.63–1.29)0.571.000.86 (0.56–1.31)0.83 (0.53–1.28)0.38
Multivariate RR (95% CI)d1.000.94 (0.67–1.33)0.92 (0.64–1.31)0.641.000.81 (0.53–1.25)0.79 (0.51–1.22)0.33
Linolenic acid (18:3), μg/mL<1.671.67–2.53>2.53<1.671.67–2.53>2.53
Sum of tumors, n242274184177210121
Basic RR (95% CI)c1.001.00 (0.72–1.37)0.78 (0.55–1.09)0.131.000.92 (0.62–1.36)0.91 (0.62–1.35)0.02
Multivariate RR (95% CI)d1.000.95 (0.69–1.31)0.77 (0.55–1.08)0.131.000.62 (0.41–0.84)0.61 (0.40–0.92)0.02
EPA (20:5), μg/mL<9.249.24–13.28>13.28<9.249.24–13.28>13.28
Sum of tumors, n197285218146212150
Basic RR (95% CI)c1.001.25 (0.90–1.74)0.88 (0.62–1.24)0.301.001.23 (0.82–1.83)3.24 (1.86–5.64)0.18
Multivariate RR (95% CI)d1.001.19 (0.86–1.66)0.86 (0.61–1.22)0.271.000.80 (0.53–1.22)0.89 (0.47–1.71)0.15
DHA (C22:6), μg/mL<36.4236.42–47.68>47.68<36.4236.42–47.68>47.68
Sum of tumors, n210242248151174183
Basic RR (95% CI)c1.001.00 (0.71–1.40)0.95 (0.67–1.36)0.771.000.96 (0.63–1.47)1.07 (0.74–1.55)0.63
Multivariate RR (95% CI)d1.000.97 (0.69–1.36)0.96 (0.67–1.36)0.811.000.90 (0.59–1.39)0.69 (0.44–1.09)0.57
Sum of omega-6, μg/mLe<348.9348.90–408.01>408.03<348.9348.90–408.01>408.03
Sum of tumors, n289228183225157126
Basic RR (95% CI)c1.000.92 (0.66–1.26)0.72 (0.52–1.00)0.051.000.96 (0.64–1.42)0.96 (0.64–1.43)0.01
Multivariate RR (95% CI)d1.000.94 (0.68–1.29)0.71 (0.51–0.99)0.041.000.60 (0.41–0.89)0.59 (0.39–0.88)0.01
Linoleic acid (C18:2), μg/mL<228.23228.23–273.44>273.44<228.23228.23–273.44>273.44
Sum of tumors, n263263174206185117
Basic RR (95% CI)c1.001.14 (0.82–1.56)0.74 (0.53–1.03)0.081.000.99 (0.67–1.46)0.98 (0.66–1.44)0.009
Multivariate RR (95% CI)d1.001.17 (0.85–1.61)0.72 (0.52–1.02)0.061.000.58 (0.39–0.87)0.54 (0.35–0.82)0.005
AA (C20:4), μg/mL<113.45113.45–139.72>139.72<113.45113.45–139.72>139.72
Sum of tumors, n252264184194188126
Basic RR (95% CI)c1.001.19 (0.86–1.64)0.79 (0.57–1.11)0.131.001.20 (0.81–1.77)1.20 (0.81–1.78)0.18
Multivariate RR (95% CI)d1.001.19 (0.86–1.64)0.80 (0.57–1.11)0.141.000.77 (0.52–1.15)0.76 (0.51–1.14)0.27
Omega-3/omega-6 ratio<0.130.13–0.16>0.16<0.130.13–0.16>0.16
Sum of tumors, n211219270143162203
Basic RR (95% CI)c1.000.84 (0.60–1.18)0.95 (0.67–1.34)0.871.001.10 (0.73–1.68)1.10 (0.71–1.68)0.51
Multivariate RR (95% CI)d1.000.86 (0.61–1.21)0.93 (0.66–1.31)0.761.001.15 (0.77–1.74)1.15 (0.76–1.74)0.51

Abbreviation: AA, arachidonic acid.

  • aAll P values from two-sided tests.

  • bSum of omega-3: linolenic acid, EPA, DHA.

  • cBasic RR adjusted for age, sex.

  • dMultivariate RR adjusted for age, sex, freckling on back, treatment allocation.

  • eSum of omega-6: linoleic acid, AA.